1. Field of the Invention
The present invention relates to an apparatus and method for use with a speech signal reproduction apparatus such as a tape player, VCR, multimedia equipment, computer or the like, for reproducing speech signals stored in a storage medium at variable speeds while preventing any degradation in tone or loss of the speech signals from occurring.
2. Description of the Related Art
In conventional tape or video players, the reproduced audio tone typically will vary when the play-back speed of the recorded signal is varied. That is, when the play-back speed is high, the audio signal being played back will vary from its original audio level and is heard as a "peep-peep" sound. At a low play-back speed, however, the audio signal will have what is known as a "loosened tape sound".
These phenomenons occur because the levels of frequency and pitch components of the recorded audio signal varies in relation to a variation in the play-back speed of the audio signal. A conventional method for preventing such phenomenons by partially playing back audio signals which have been read into a memory buffer is set forth in Japanese Patent Laid-Open Publication No. Heisei 4-168499 (Jun. 16, 1992). In accordance with this method, when the play-back speed is doubled, the audio signals that were read into the memory buffer are partially played back in such a way that only one of each of its two successive time-slices is played back.
For example, when a vocal recording of "I go to school with Jane" is played back at double speed in accordance with this conventional method, components of the original speech signal, which respectively correspond to the shaded portions shown in FIG. 1, are eliminated, so that only the speech "I to with Jane" is reproduced. Hence, since the conventional method plays back only a portion of the speech at a higher play-back speed so as to keep the tone of the speech in tact, the original meaning of the speech is lost. As a result, it is very difficult to understand the meaning of the speech using this conventional reproduction method.